I wanted to share a new idea as I continue to develop my P60 drop in and would like feedback from the community.
I started thinking about a way to solve a problem many people have with 18650 lights ’battery too long battery too short’
It’s not just the battery, it’s the host too…some battery compartments seem to be made for unprotected cells…but, I’ve come across
a few that are a tight fit for the shortest unprotected cells. Enter the double spring -the springs give a lot of latitude for various sized
batteries, but adds a lot of resistance to the system. Copper alloy springs are excellent conductors, but the best fall short of the durability
of a good steel spring and may need to be replaced occasionally.
Last week, I was building drop ins for 2 people with special requests:
- Using a ZeroRez switch and needed a longer spring
- Had a host that needed an incredibly short spring to handle a protected 18650
So, here’s my solution (I’ve built 2 for the special request and 3 more to play with and test)
The threaded portion is brass, the screws are brass, the button contact is brass and the springs are Copper alloy.
I found no detectable lumen drop from this system vs a straight spring.
To replace a spring, screw one out, screw another in or screw in a flat contact for maximum space savings. People who mount their lights on a gun must have
two springs and if they shoot much, the springs weaken quickly…wear one out, screw another on.
I’m showing 2 contact options -Copper alloy spring and Brass Button Contact. I’m thinking about adding a tall button contact and a short spring.
Most of you may find this not to be a problem, but all of my drop ins are potted. If they were not potted, just solder on a new spring -still, not very convenient.
…so, let me know what you think, do you have any experiences with tight fits, crushed springs or dented battery protection circuits?